Breech and firing mechanism for recoilless firearms



1951 w. J. KROEGER ET AL 2,537,063

BREECH AND FIRING MECHANISM FOR RECOILLESS FIREARMS Filed Feb. 2, 1949 3 Sheets-Sheet 1 a W ATTORNEYS.

1951 w. J. KROECIEER ETAL 2,537,063

BREECH AND FIRING MECHANISM FOR RECOILLESS FIREARMS Filed Feb. 2, 1949 3 Sheets-Sheet 2 FIG. 8.

Jan. 9, 1951 w. J. KROEGER ETAL BREECH AND FIRING MECHANISM FOR RECOILLESS FIREARMS 3 Sheets-Sheet 3 Filed Feb. 2, 1949 Ail v 4 INVENTO KROEGER. musssa.

WILLIAM J.

C. WALTON ATTORNEYS.

Patented Jan. 9, 1951 BREECH AND FIRING MECHANISM FOR RECOILLESS FIREARMS William J. Kroeger and Clarence Walton Musser, Philadelphia, Pa.

Application February 2, 1949, Serial No. 74,164

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 3 Claims.

y Therefor.

Our invention relates to firearms of the recoilless type, and it has special reference to nonrecoil guns wherein the forces of rearward reaction that result from projectile discharge are neutralized by forwardly acting counterforces simultaneously set up by the propellent charges combustion.

Broadly stated, the object of our invention is to improve the design and extend the usefulness of recoilless guns wherein the named recoil neutralization is effected by a rearward escape of generated powder gas through openings or orifices in the guns breech.

A more specific object is to provide improved chamber and breech constructions for such recoilless guns.

A further object is to increase the simplicity, ruggedness and compactness of breech actions and of firing mechanisms for recoilless firearm use.

An additional object is to provide improved means for loading and firing the gun.

Other objects and advantages will become apparent as the disclosure and description hereof proceed.

In the aforementioned parent application we disclosed a number of factors to be necessar for a satisfactory operation of our inventive recoilless firearm. In constructing one recoilless firearm pursuant to that disclosure we: (a) make the guns chamber of substantially larger diameter than the ammunition cartridge case which fits therein; (b) support this cartridge case centrally in the enlarged chamber solely from the two ends of the case; provide in the guns breech a rearwardly opening orifice of unique annular noz-.

zle design, that is capable of ready adjustment for optimum area; (d) use a cartridge case having a metal wall which is perforated throughout the length and circumference of the case and which permits discharge of propellent combustion gases radially against the chambers surrounding wall and thence rearwardly from the gun out through the annular orifice of the guns breech; (e) pro-engrave the projectile for ready passage through the rifled bore of the guns barrel; and

( so coordinate the breech and firing mechanisms as to permit quick and convenient loading and firing.

The invention to which the present specification is essentially restricted is the specific breech closure structure and firing mechanism used in the gun first disclosed by the aforementioned parent application. The present invention itself, together with illustrative embodiments thereof will best be understood from the following description taken in conjunction with the accompanying drawings wherein:

Fig. 1 is a rear view of a recoilless gun of mm. caliber which incorporates our inventive features, and is shown with the breech bar thereof horizontal and the breech block secured within the chamber where it constitutes the inner wall of an annular orifice;

Fig. 2 is a similar view to that of Fig. 1 except that the breech bar and breech block are shown after having been rotated to the unlatched position;

Fig. 3 is a rear perspective view of the gun with its breech block withdrawn from the chamber and swung downwardly on a supporting hinge;

Figs. 4-5 are enlarged showings of open" and closed breech looks with which the weapon is provided;

Fig. 6 shows in detail the breech block supporting hinge;

Fig. 7 shows the hinge of Fig. 6 in front side perspective and with its hammer rollers in place;

Fig. 8 is a section on line 8-8 of Fig. 1 showing further details of the breech block, locking devices therefor, the firing mechanism, and trigger linkage;

Fig. 9 is a section on line i0|0 of Fig. 1 through hinge and breech bar rollers by which the firing mechanisms hammer is cooked upon each unlatching of the breech;

Fig. 10 is an enlarged section on line l0l0 of Fig. 8 through the guns trigger handle with the trigger and associated safety mechanism in place therein;

Fig. 11 is an enlarged section on line I l-H of Fig. 8 similar to Fig. 10 but taken from a different level of the trigger handle;

Fig. 12 is a view taken from line l2-l 2 of Fig. 8 to show from another vantage point the relationships of the trigger, the trigger key and the safety button;

Fig. 13 is a section on line i3-l3 of Fig. 3 showing details of the breech block and trigger handle when in the open breech position;

Figs. 1415-16-17-18 are views illustrative of '3 how cocking of the hammer is eifected by each unlatching rotation of the breech bar; and

Fig. 19 is an enlarged reproduction of the hammer and cooking roller mechanism first illustrated by Fig. 9.

The complete recoilless gun Our inventive improvements are here illustratively disclosed as being incorporated in a mil tary weapon of '75 mm. caliber capable of a completely recoilless firing of projectiles. As the de scription proceeds, it will become apparent that our improvements may also be applied to firearms of characters, sizes, and shapes other than the one here disclosed and that the represented '15 mm. open breech weapon thus has been chosen only to illustrate and not to limit the inherently wide application and scope by which these im-v provements are characterized.

I 'he illustrative recoilless firearm here shown eonsists of a barrel 39; an enlarged chamber 3! secured to the rear of this barrel and having the uniquely tapered shape represented; a breech bloch 33 partially closing (see Figs. 1-2) the rear of the chamber; a breech bar 3 secured to the block and carrying trigger and breech handles 35:35; a pair of carrying handles 3"i33 (see Fig. 3) and a sight (not shown) for aiming the gun in conventional manner.

As here represented the carrying handles til-3i? are suitably clamped to the barrel 25% as shown 7 These handles, in conjunction with the trigger and breech handles ss ss enable two or four men readily to carry the weapon from one location to another.

Ammunition having a novel perforated cartridge case (only the rear or base end of the case is shown at in Fig. 8, the perforations in the wall of the case being further along the sidewalls thereof and are not shown in the drawings) is loaded into the weapon from the breech thereof in a manner presently to be explained. Such loading may be done either by the man who fires thev weapon or by an assistant.

The chamber and breech As here shown, the guns chamber 35 takes the form of an enlarged cylinder uniquely tapered at its forward end and there afiixed to the rear of barrel 3!} in an integrally secure manner as by the aid of screw threads (not shown). In Fig. 3 this juncture of the barrel and chamber is represented by the flange 55 which encircles the forward end of the tapered chamber. The inner, most side of this flange (not shown) bears the threads which are used to secure barrel 3i; thereto.

As the drawings also show, the guns breech block is a spider-like element removably secured within the rear end of chamber 31 and constitutes only a partial closure therefor. It takes the form of a cylindrical block 33 which is her to form a substantially annular orifice that leads from the chambers interior to the rear exterior of the gun. As reference to Figs. 1-2-3 .radially spaced from the chamber wall in a manthreads are engaged, as in Figs. 1 and 8, they securely lock the breech block 33 within the rear of the chamber 3!.

The chamber wall spaces which circumferentially separate the locking protrusions 53 have a diameter larger than the maximum for the breech lugs 4S and this relationship enables free longitudinal movement by these lugs through the spaces named. This movement is utilized in inserting the breech block within the chamber and also in withdrawing the block therefrom, all in a manner presently to be described.

When inserted and locked within the chamber 3!, as shown in Figs. 1 and 8, this breech block 33 constitutes a firm support for the ammunition which it helps to position within the weapon. The steel of its central core structure is of sufficient thickness and strength to stand, with a factor of safety of well over two, the maximum rearward thrust exerted thereon during firing.

Cooperating with the guns barrel and the just described chamber and breech structure is ammunition having the earlier mentioned unique perforated case (only the rear end of which is shown at M in Fig. 8. As explained in greater detail in the aforementioned parent application, the purpose of the perforations (not here shown) in cartridge case if is to permit the powder gases to issue therefrom in a radial manner, so as to expand within the enlarged chamber 3! and become exhausted through the annular orifice 4.8 to the rear exterior of the gun with a torque equal but opposite in direction to that caused by a projectile (not shown) upon being fired through the guns barrel.

In the loaded position represented by Fig. 8 the cartridge case head 63 is accordingly engaged by a mating recess 533 in the front of the breech block. This recess I35 flares outwardly toward the front so as more conveniently to receive the case head during loading. By its en agement with the head, the rear of cartridge case 4% is centrally positioned within chamber 31 and the entire case is restrained against backward movement. Thus positioned, the primer (which is. carried within the primer percussion element 56 shown in Fig. 8) carried by the cartridge, case head 63 is engageable a firing pin 66 protruding through the center of the bree h block 33 and there actuated by firing mechanism later to be described.

When the primer is so, engaged a booster powder charge 58 contained in booster tube 5'! is ignited and the flame therefrom spreads through openings 58 in the wall of tube 53' and thereby ignites the propellent charge 55. Ignition of. the propellent charge causes the expulsion of the ammunition rounds projectile (not shown). from the un.

The annular orifice and recoil neutralization The 75 mm. recoilless firearm illustratively here shown effects. recoil neutralization in the unique manner taught by our earlier mentioned oo-pending application Serial No. 577,830; that is, the forces of rearward reaction are neutralized by forwardly acting counterforces. These countenforces are produced by acceleration of the rearwardly escaping generated powder gases, with an accompanying pressure gradient within the chamber and venturi. Therefore, the pressure forces rearwardly acting against the obstruction presented by the breech can be, counteracted by the forwardly acting pressure forces acting on the small annular forward portion of the chamber 3|, the forwardly acting drag forces of the projectile (not shown) in the rifled barrel 30, and by the forwardly acting force components produced by the pressure of expanding gases in the conical and divergent portions of the earlier indicated annular orifice -%8 between the guns breech block 33 and the rear wall of chamber 3| wherein this block is secured.

As the drawings clearly show, this annular orifice extends all the way around that block's central core and is obstructed only by the four radial lugs 49 which engage with the four mating protrusions 50 of chamber 3!. All circumferential space between these lugs thus constitutes the named-annular orifice 8 which leads from the interior of chamber 3| rearwardly to the exterior of the gun.

. Upon ignition of the propellent powder 55 and the resultant discharge of the projectile (not shown) forwardly out of barrel 30 there is expelled through the perforations (not shown) of cartridge case fill combustion gases which are projected radially against the surrounding chamber wall and. then rearwardly out of the chamber through the annular orifice now being described. By thus acquiring momentum opposite to that of the forwardly moving projectile (not shown) the explosive gas thus expelled sets up the aforesaid counterforces which tend to neutralize recoil.

In our improved 75 mm. weapon here shown we supplement this momentum effect by making the guns annular breech orifice 48 of the represented nozzle or cone shape indicated best by Fig. 9. Starting with a relatively narrow radial width at its front or throat, the annular orifice flares inwardly toward the rear with an angle spread of approximately 20. Such an angle yields a satisfactory forward force component due to an expansion of the powder gases in passing rearwardly through the orifice as earlier explained.

For maximum effectiveness it would be desirable to extend the annular or nozzle orifice to a substantial axial dimension, but practical considerations show that acceptable performance is achieved when the nozzle orifice has the relatively short length which the drawings indicate. (See Fig. 9 in particular.) Thus, we prefer to select for the nozzle an axial length which gives a rear or discharge area of approximately two and onehalf times the area of the orifices front or throat area. Dimensions other than that shown may of course be utilized with varying degrees of relative efiectiveness.

In our achievement of complete neutralization of recoil we find that there exists an optimum ratio between the bore area of the guns barrel and the throat area of the breech orifice. The factors which determine the value of this optimum ratio are more completely appraised by our earlier mentioned co-pending application Serial No. 577,830 and other cases to which reference has therein been made. As those cases show, the required bore-to-throat area ratio is dependent primarily upon the amount of expansion obtained in the nozzle 48 and to a lesser extent upon such factors as the relative weights of the powder and projectile. In a firearm of the annular orifice type here disclosed this ratio for zero recoil is found to lie within a range from about 1.40 to about 1.60.

.Our improved weapon includes provision for adjusting this ratio to the optimum value which during actual firing does in fact produce zero recoil. In the illustrative arrangement disclosed, this provision takes the form of a breech orifice cone 54, secured in the position illustratedun Fig. 8 by four screws II (also see Fig. 3), which also serves in conjunction with breech block 33 to support the rear of cartridge case 40. It will be noted that cone 54 determines the weapons ratio of bore area-to-throat area as a result of its defining the forward interior wall of the weapons annular orifice shown at 48 in Fig. 9. As that figure further indicates, the rear interior wall is defined by the breech block 33 when same is secured within the chamber.

While occupying such a portion of the total orifice area as is needed to provide the necessary adjustment, this cone 54 does not alter the basic nozzle shape thereof and hence it constitutes a particularly efficient means for effecting the required adjustment. The maximum throat area is of course realized when the outside diameter and axial length of cone 54 are relatively small; hence the smallest side of the adjustin cone is selected to afford a throat area large enough to meet the maximum requirements.

Applying the figures earlier stated, use of such a minimum diameter cone might give a bore-area to throat-area ratio of the 1.40 lower limit. To change this ratio to the other extreme of the named 1.60 maximum, it is merely necessary to install an adjusting cone 54 of sufliciently larger diameter and axial length as to cut down the total throat area by the requisite amount; and to obtain ratios of intermediate values, there may be substituted adjusting cones 54 of varyin intermediate sizes.

Choice of the exact preferred cone size is most effectively determined by trial firing in a pendulum or other gun suspension which is free to swing and thereby indicate the presence, direction and magnitude of recoil should same exist. In the illustrative mm. weapon represented, zero recoil is found to call for an adjusting cone which gives a bore-area to throat-area ratio of the order of 1.48. With such adjustment the nozzle throat has a total area which is approximately one-tenth of the cartridge case's total area of preforations (not shown).

Neutralization of rotational reaction As pointed out by our co-pending application Serial No. 577,830, firearms with rifled barrels experience a rotational reaction by virtue of the spinning motion that firing imparts to the projectile (not shown). Depending on the direction of the barrels rifiing, the projectile (not shown) will be given a clockwise or counterclockwise rotation. Whatever the direction of this rotation, the result thereof will be an imparting by the projectile of a torque in the opposite direction but of equal magnitude to that received by the barrel.

Our improved 75 mm. weapon here shown includes provision for neutralizing such reactive torque by causing the explosive gases which rearwardly discharge through the annular breech orifice 48 to impart to the weapon counterbalancing torque of the same magnitude as that which the rifled barrel imparts to the projectile. This provision is eifected by so specially shaping the chamber protrusions 50 and breech block locking .lugs 49 that the gases passing through orifice 48 have angular momentum imparted thereto.

Each of these lugs 49 and chamber protrusions 50 has sidewalls that are slightly out of parallel with the guns axis. This side wall arrangement is such that the powder gases flowing rearwardly through the orifice as are made to rotate about the guns axis. By reason of this counter.- acting spin thus given to the gases, there is imparted to the chamber 3| a torque counteracting shown by Figs. 3 and 13.

that applied by the projectile (not shown) Only the relatively small degree of angular twist shown is found sufficient to make the thus imparted torque of the same magnitude as the barrel 3t imparts to the projectile (not shown) 'in advancing it through the rifled bore.

All neutralizing torque thus set up by the escaping gases is exerted on the sides of the locking shaping the chamber protrusions and lockin lugs 49 in the opposite sense.

Breech blocks withdrawal from chamber Explanation has already been given of how the breech block 33 is secured in the rear of chamber .3I by the aid of that blocks locking lugs 59 and the mating protrusions 53 on the chamber interior. In the engaged position represented by Figs. 1, 8 and 9 this support is all that is needed to hold the breech block in place, and it is fully adequate to restrain the maximum chamber pressures which combustion of the propellent charge 55 sets up.

To facilitate loading and removal of the cartridge case to after firing, provision is made for releasing this breech block 3?. from its chamber attachment, rearwardly withdrawing it from the chamber 31 and swinging itcut oilgnment with the chamber interior to the downward position The earlier mentioned breech bar 35 to which the forwardly extending handies 3 35 are 'amxed comes into play during these actions.

Then also utilized is a hinge support fixture having its upper end connected with breech block 33s center and'its lower end connected through a hinge pin 83 and an attachment block: '56 (see Figs. 3 and 13) to chamber sis lower sidewall. Through these elements the breech block 8s continues to receive support from the gun after it has been withdrawn from the chamber.

The earlier mentioned breech bar is secured to the breech block 33 by means of four bolts shown at H in Figs. 1-2. Intermediate this bar and the main body of the block is an offset ringlike extension is of the hinge fixture 25. Around this ring extension both the breech block 33 and the bar 3d may be turned between the horizontal bar position of Fig. l and the inclined bar position of Figs. 2-3; In the gun here shown the range of this angular movement is of the order of 45 degrees, as contrast of Figs. 1 and 2 will indicate.

counterclockwise rotation of the weapons established by those portions of the hinge support at the limit of counterclockwise rotation wherein.

the breech block is securely locked in this chamber 5i; the latter figure shows the bar and block at the clockwise limit of rotational travel in which the block has been freed for withdrawal from the chamber.

Serving to support the breech block upon such withdrawal is the earlier mentioned hinge fixture 55 secured at its lower end to chamber wall 3i as already described. Once disengaged from cham ber 3i as shown in Fig. 2, the breech block 33 plus bar 34 and handles 353t are free for rearward withdrawal and downward swinging around hinge pin to the position represented by Figs. 3 and 13.

When the breech block 33 is withdrawn from chamber 3 I the entire interior area of that chamber is unobstructed in a way permitting ready insertion of a projectile (not shown) and cartridge case 49 into the gun or ready withdrawal 5 a fired cartridge case from the weapon.

To reinsert the breech block into the chamber, it is merely necessary to swing the block upwardly from the position shown in Figs. 3 and 13; move it forwardly into the chambers open end as indicated by Fig. 2; and finally give handles and bar it a turning movement which brings the block to its counterclockwise limit of rotation in which the locking lugs 49 thereof engage the chambers mating protrusions as shown in Figs. 1 and .8.

The open breech lock Our improved weapon here illustrated utilizes two locking devices by which the breech block 33 is respectively secured in the inclined bar position of Figs. 2 and 3 and in the horizontal position of Fig. 1. The first of these devices will be spoken of as the open breech lock and the second as the closed breech lock.

The purpose of the open breech lock is to keep the breech block 33 and its attached bar 34 in the inclined position of Figs. 2-3 at all times except when the block is fully inserted into the guns chamber at. This lock thus serves to hold the bar as and the breech block 33 in the inclined position of Figs. 2-3 as long as the breech block remains withdrawn from the chamber, as in Figs. 3 and 13.

The mechanism utilized includes a locking bar 32 having the general shape which Figs. l and 13 show; a slot 83 cut into the forward face of hinge fixture '55 as shown in Figs. 6, 7 and 13 for accommodat-ing bar 82 as shown in Fig. 13; a slot 84 cut into the rear face of breech block 33 as shown by Figs. 1 and i3 for at times receiving a portion of bar as as shown in Fig. 13; and a leaf spring 35 beneath the bar in hinge slot 33 as shown in 13 which urges that bar toward the breech block.

As long as the breech block 33 is fully inserted into the chamber M, the bar 82 is held completely within the hinge slot 33 by contact of the forward face of the bar with the rear face of the chambers lower pro-tusion 5 Under this condition the bar 82 is completely withdrawn from engagement'with the. breech block slot 84 and no rotative restraint is imparted thereby to the breech block. Insofar Once, howeverythe breech block 33 is withdrawn from chamber 3|, leaf spring 85 then pushes bar 82 into the breech block slot 84 as soon as that slot is brought into alignment with the bar. From Figs. 1-2-3 it will be seen that such alignment is eifected When the breech block is rotated to the fully unlatched position which Fig. 2 shows. In that position the bar moves forwardly into the breech block slot as indicated by Fig. 13.

Such movement locks the breech block 33 against potential movement with respect to hinge mounting 75, in the forward slot 83 of which the bar 82 is carried. Such locking action continues as long as the breech is withdrawn from the chamber. It prevents, for example, the handles 35-35 and the breech bar 38 from being moved out of the inclined position which Figs. 2-3 represents. Such prevention is made especially desirable by certain operating characteristics of a unique firing mechanism later to be described.

Upon reinsertion of breech block 38 into the chamber 3|, locking bar 82 is once again pressed completely into its hinge slot 83 as indicated in Fig. 2 by contact of its forward face with the rearward face of the chambers lower protusion 59. This breaks the lockbetween breech block 33 and hinge mounting l5 and allows the block to be turned by handles 3536 and bar 34 from the disengaged position of Fig. 2 to the chamber-engaged position of Fig. 1.

The closed breech block The closed breech block earlier mentioned now becomes effective to hold the breech block 33 in this horizontal bar position of Fig. 1 until after the weapons firing pin 86 moves forward. The mechanism utilized includes a closed locking pin and bar combination 88-89 as shown in Figs. 5 and 8 and assembled with the breech block 33 and breech bar 34 as shown by Fig. 8; a slot 99 cut into the right side of hinge ring 19 as shown in Figs. 6 and 8 to be engaged bylocking bar 89 as indicated by Fig. 8; a spring 9| which urges the rear of bar 89 into hinge slot 99 as indicated by Fig. 8; and a firing mechanism hammer 92 having on its side wall a groove I96 whose bottom is tapered so as conveniently to engage anend of bar 89 in the manner also shown by Fig. 8.

This hammer 92 is carried within a hollow case 93 which is integral with and extends back from the breech bar 34 in a manner indicated by Figs. 8, 9, 13 and 19. As will later be explained, this hammer is moved rearwardly to the cocked position shown by Figs. 8 and 13 upon each unlatching rotation of breech bar 34; and it is released for forward advancement to the fired position shown by Figs. 9 and 19 upon each depression of the guns trigger 94 in handle 35.

As long as hammer .92 is cooked, the taper of groove I96 in the side wall thereof (indicated by Fig. 8) allows spring 9| to force locking bar 89 inwardly into engagement with hinge ring slot 98 (Fig. 8) and thereby restrain the breech block and its bar 34 from rotative movement with respect to the hinge. This assures that the breech bar must remain in its chamber-engaged position of Figs. 1 and 8 unless either the hammer 92 moves forwardly to the position of Figs. 6, 9 and 19 or unless locking pin 88 (Figs. 1, 2 and 8) is manually moved to the right against spring 9| (see Fig. 8).

Upon release of hammer 92 to its forward or fired position of Figs. '9, 17 and 19 the slow taper of groove H18 in that hammers side wall wedges bar 89 outwardly against spring 9] and thereby moves that looking bar out of the hinge rings slot 90. (See Fig. 6.) This wedging action imposes such small restraint upon forward movement of the hammer that it in no way interferes with the desired operation of our weapons firing mechanism.

Each firing of the weapon therefore autopushed to the right against spring 9! (see Fig. 8). 7

Such pushing releases the breech block for clockwise rotation and withdrawal out of the chamber even though the weapoi'is hammer 92 may be cooked as indicated by Figs. 8, 13 and 18.

The firing mechanism For igniting the ammunitions propellent charge 55 at the will of an operator use may be made of any suitable firing mechanism; Here represented by way of illustration is a unique mechanical type of firing mechanism by the aid of which an operator may fire the weapon by a simple depressing of the earlier mentioned trigger 94 carried by handle 35.

In the disclosed arrangement the firing pin 66 carried by the guns breech block 33 receives through direct attachment with the earlier mentioned hammer 92 a firing blow created by the forward movement of that hammer. The force incident to that forward movement originates in a spring 9'! carried between the hammer 92 and case 93 as most clearly shown in Figs. 8, 9, 13 and 19. This force is made available for firing thegun when a scar shown at 98 in Fig.8 is withdrawn from in front of the hammer.

The illustrated hammer 92 takes the form of a metal cylinder having the general appearance best indicated by Figs. 13 and 18 inclusive. The

firing pin 86 is screwed into the front of this cylinder and thus at all times moves in'unison therer with. This movement is between the cookedposition of Figs. 8, 18 and 19 and the fired position of Figs. 9, 1'7 and 19.

Cooking of the hammer I90 and at H)! in Figs. 14 to 19, inclusive.

Rollers I 90 are carried by the hinge ring 19 (see Figs. 7 and 19), while rollers l9| are carried by the breech bar 34. Both sets of the named rollers engage with longitudinal slots H13 in the outer surface of hammer 92. The forward portion of each of these slots is tapered as shown at I04 in Figs. 13, 14, 1'7, 18 and 19. l

With the breech bar 34 in the horizontal position of Fig. 1 both sets of these rollers l00| Ill lie along line 99 of Fig. 1, and sections therethrough appear as shown in Figs. 9 and 15. The Y hammer 92 is shown by Figs. 9' and 17 in its forward or fired position wherein firing pin 66 has by the hammer and spring 91 been moved to its forward limit of travel.

Upon rotation of the breech bar 34 from the horizontal position of Fig. 1 to the inclined bar position of Fig. 2 the forward or hinge rollers -0 remain stationary, while the rearward or bar rollers, I III rotate the hammer clockwise as viewed from, the rear, from the position shown in Fig. 15, to that indicated by Fig. 16. Fig. will be seen to correspond to Fig. 14, except that the latter shows the hammer and it rollers as viewed from the front end of the gun in Fig. 8, while the for mer shows the same part as viewed from the rear or breach end of the gun. Fig. 16 is similar to Figs. 14 and 15, except that in Fig. 16 the hammer and its. rollers are shown in the position they assume when the breech bar 34 is turned to the inclined position of Fig. 2, whereas in Fi s. 14-15 the hammer and its rollers are shown in the position they assume when the breech bar 34 is in the horizontal position of Figs. 1 and 8.

The named rotative movement brings the tapered sides I04 of the hamme slots I03 against stationary rollers I00, and by a camming action best ap arent from Figs. 17-18 forces the hammer 92 backwards against spring 91 and into the cocked position shown by Figs. 8 and 13. When the cooked position has been reached the sear shown at 98 in Fig. 8 is by spring action later to be described forced inwardly ahead of the rear face of a restraining slot shown at I 40- in Figs. 8-9-.

Release of the hammer In this position the sear 98 holds the hammer cocked until such time as trigger 94 may be depressed. Upon such depression of the trigger thesear is withdrawn from its engagement with the restraining slot I40, and hammer 92 plus firing pin 66 are allowed to move forward due to the expansive force of spring 91. This forward movement brings firing pin 66 against the ammunitions primer 56 and thereby fires the weapon.

The named forward movement can, of course, take place only after the breech bar 34 has been returned to the horizontal position of Fig. 1. In

that horizontal position bar rollers IOI are again realigned with hinge rollers I00 as shownv in Fig. 15. Thi realignment frees the hammer for un restrained forward movement as soon as sear S8; is withdrawn from the latching slot I40 therein.

In the illustrative construction shown hammer 92- is fitted relatively close to the inner walls of hammer housing 93. In order that air pumping action resulting from the closeness of this fit will not restrain longitudinal movement ofthe hammerwith respect to the casing, there is provided in the hammers sides a second pair of: longitudinal slots indicated. in I01 in Figs. 8,. 14, 15 and 16. These slots allow free passage of air into the space behind the hammer upon forward or firing movement thereof,v and from that rearwardspace, uponbackward or cooking movement thereof.

Complete hammer o eration" shown by Figs. 9 and 19' while the breech block 33 i still" locked in chamber (H with the bar 34 horizontal as shown in Fig; 1.,

Rotation of the breech bar- 04 to the inclined position shown in Fig. 2 causes the bar rollers I'B-Ii to rotate the hammer 92 clockwise asviewed from the rear, and this action in turn causes hinge rollers I00 to cam the hammer 92 backwardly against spring 91 as already explained by reference to Figs. 8, l3 and 18. The so-cocked hammer now occupies the position shown by Figs. 8'

and 13. Retention in that position is effected by sear 98 blocking forward movement of the hammer as shown in Fig. 8.

This blockin continues during subsequent withdrawal of the breech block 33 from the chamber to the position shown by Figs. 3 and 13. It also remains efiective during reinsertion of the breech block into the chamber and engagement therewith by restoration of breechbar 34 to the horizontal position of Fig. 1. Such restoration re-aligns rollers I00--IOI from the condition shown by Fig. 18 to that indicated by Fig. 14.

This realignment conditions the hammer for subsequent forward movement upon withdrawal of the restraining sear 98. Upon such withdrawal spring 91 forces the hammer and it firing pin 66 rapidly forward into contact with the cartridge cases primer 56 and thereby detonates the primer and fires the weapon. By this action the firing mechanism is returned. to the original after firing condition with which this description started.

The trigger mechanism at 34- in the same figure a protruding from the forward end of trigger handle 35; and a rotatable safety button I09 carried in the hollow end of that handle as also shown by Fig. 8.

The sear takes the form of a round rod slidably housed in the left half of breech bar 34 between the rear wall of that bar and a front cover plate I00 and having an outer end which is inclined as shown by Fig. 8 into a mating opening in the inner end of the plunger-like trigger 94. This trigger is axially movable withinv handle 35 and safety fixture I09, but is by a key III prevented from rotation with respect thereto. By a double action of a trigger spring I II] this trigger 94, when not compressed into firing position is urged toward its outward limit of travel. This travel limit normally would be the. safety buttons opposed lower or inner projections H4; however, the intervening agency of the spring H0, being connected to the safety button below the projections H4 and also connected to. the trigger 94, limits such travel to the distance over which spring I I 0 may be compressed against projections H4. Such urging holds sear 98 against hammer 9?. as shown in Fig. 8..

Reference to Fig. 8 shows that spring. H0, not only exertstension between parts 94 and I09 but that it is also arranged to impart turning effort on safety button I 09 with re pect to trigger 94 as will be more fully explained below.

Incident to this turning effort use is made of the key III which passes through an opening in the trigger 04 and by engagement with longitudinal slots H2 inside the trigger handle 35 prevents rotation of the trigger within that handle while at the same time permitting axial trigger movement with res ect to the handle.

Safety button I 09' is provided with side slots I50 through, which the ends of trigger key III pro- 13 spring III! encircles the trigger rod 94 as shown in Figs. 8 and 13. The two ends of this spring respectively are attached; (a) to an enlarged portion of that rod shown in Figs. 8 and 13 at the sear engaging end thereof; and (b) to the inner end of the safety fixture I 539 (again see Fig. 8).

During assembly of the parts shown in Fig. 8 this spring is so wound onto its two end attachments that upon insertion of the trigger key III through the safety slots I50 and the trigger, the safety button Iilfi has exerted thereon a torque tending to rotate it clockwise with respect to the trigger. (In this and later references to rotative direction with respect to the trigger, the directions shouldbe considered as they would appear when. viewed from the triggers outer end-i. e.,.

where it protrudes from handle 35toward the triggers opposite or inner end.) This rotative urge positions the safety slots I59 as shown in Figs. 8 and 12 and thereby safeguards the trigger 94 against accidental depression into the guns handle 35.

Loading and firing From the foregoing it will be seen that we have provided an improved recoiless firearm which offers important advantages connected with both loading and firing. To place the ammunition round within the weapon it is merely necessary to unlock the breech block 33, withdraw it from the chamber 3| and swing it downwardly to the position shown by Figs. 3 and 13, thus completely freeing the chamber opening.

The ammunition round (only the cartridge case All of which is shown in the drawing) is now inserted into the open chamber and the rear of the barrels bore. When the projectile (not shown) is thrust home in the barrel, centering support is imparted to the forward end of the cartridge case, case head 63 being similarly centered within chamber 3I due to the heads abutting with the breech cone 54.

The breech block 33 (together with bar 34 and handles 3538) is now moved upwardly and forwardly into the chamber. In approaching and engaging with the cartridge case head 53 the flared recess I38 in the breech blocks front comes into abutment with the head and thereby restrains the case against rearward movement.

counterclockwise rotation of the breech block by bar 3d and handles 35-36 now looks that block into the chamber with the case heads rim in abutment with the breech cone 54 and the case head proper in abutment with the breech block, the primer 56 in alignment with the firing pin 65 and the entire cartridge case 40 centrally positioned within the surrounding chamber 3i.

lhe hammer 82 now has the cooked condition shown by Figs. 8 and 13 and the weapon is accordingly ready for firing. The safety button IE9 first has to be rotated to release the trigger, whereupon a backward pressure on handle 35s trigger 94 will release the hammer and firing pin 65 to cause detonation of percussion element 56 and ignition of primer and propellent charges 58 and 55, respectively.

The resultant combustion of propellent 55 discharges the projectile (not shown) in the manner earlier described. After this firing, the fired cartridge case is withdrawn from the chamber as follows. The breech block is first unlocked and then withdrawn rearwardly and downwardly out of register with the chamber and into the position on hinge support I5 which Figs. 3 and 13 show. Extraction of the case now becomes possible. For facilitating such extraction we supplement our hinge-mounted breech block 33 by an extractor represented at I I! in Fig. 13. This ex- From the foregoing it will thus be seen that we have improved the design and extended the usefulness of non-recoil guns wherein the forces of rearward reaction that result from projectile discharge are neutralized by forwardly acting counterforces simultaneously set up by release of the powder gases through an orifice in the guns breech; that we have provided improved chamber and breech constructions for such recoilless guns; that we have increased the simplicity, ruggedness and compactness of breech actions and of firing mechanisms for recoilless firearm use; and that we have provided improved means for loading and firing the gun.

Our inventive improvements thus are capable of wide application and hence are not to be restricted to the specific form here shown and described by way of illustration,

We claim:

1. In a firearm, the combination of a chamber, a breech block movable into and out of the rearward portion of said chamber and being secured therein when rotated to a locked position and freed for withdrawal therefrom when rotated to an unlocked position, a support member for said breech block hingedly attached to the rear exterior of said chamber and extending radially into pivotal juncture with the center of said block whereby to permit rotative movement of the block between said locked and unlocked positions plus supported block withdrawal from the chamber, a bar extending across and secured to the rear of said breech block, and an operating member affixed to said bar to facilitate turning of said breech block within said chamber and to aid withdrawal of the block from and reinsertion of the block into the chamber.

2. In a firearm, the combination of a chamber, a breech block movable into and out of the rearward portion of said chamber and being secured therein when rotated to a locked position and freed for withdrawal therefrom when rotated to an unlocked position, a support member for said breech block hingedly attached to the rear exterior of said chamber and extending radially into pivotal juncture with the center of said block whereby to permit rotative movement of the block between said locked and unlocked positions plus supported block withdrawal from the chamber, an operating member affixed to said breech block for transmitting turning plus withdrawing and reinserting movements thereto, a firing pin disposed within said breech block and movable axially thereof between a forward released position and a rear cocked position, a hammer attached to the rear of said firing pin, a spring urging said hammer and firing pin towards said forward released position, means effective upon each rotative movement of said breech block from said locked to said unlocked position for camming said hammer and attached firing pin rearwardly against said spring and into said cocked position,

and trigger plus sear means efiective to engage:

said hammer and latch it in its said cocked posi tion againstthe force of said spring.

3; In a firearm, the combination of a. chamber, a breech block movable into and out of the rearwardportion; of said chamber and being secured therein when rotated to alocked position and freed for withdrawal therefrom when rotated to an unlocked position, asupport member for said breech block hingedly attached to the rear exterior of said chamber and extending radially into pivotal juncture with the center of said block whereby to permit retative movement of the block between said locked and unlocked positions, an operating member affixed to said I breech block fortransmitting turning plus with 16 ming; means eflective to move said hammer rearwardly against said spring and into said cocked position upon each rotative movement of said breech block from said locked to said unlocked position with respect to said hinge-mounted sup-- port member.

WILLIAM J. KROEGER. CLARENCE WALTON MUSSER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

